Preparation and sensing properties of hierarchical 3D assembled porous ZnO from zinc hydroxide carbonate
The precursor hydrozincite was synthesized through hydrothermal reaction and hierarchically assembled 3D porous ZnO was prepared by calcination of the precursor at 400 °C for 15 min. The 3D porous ZnO was composed of micrometer spheres which were assembled from nanoflakes. The sensor based on 3D porous ZnO showed improved ethanol response compared to 2D porous ZnO nanoplates. The highest sensitivity of 77.5, 9.8 and 49.7, respectively, for the sensor based on 3D porous ZnO-2 were obtained for 100 ppm acetone, benzene and ethanol at the operation temperature of 420 °C, 420 °C and 340 °C, respectively. The sensor also show selectivity to acetone at the operation temperature of 420 °C. The highest sensitivity of the sensor based on ZnO-3 was of 59.9 to 100 ppm ethanol, the response increased linearly with the concentration of ethanol in the range of 10–1000 ppm. All the response and recovery times of the sensors were less than 20 s. The good sensing performance of the 3D porous ZnO sensor indicated that the hierarchically assembled 3D porous ZnO could be a promising candidate for highly sensitive gas sensors.